Implement serialization for LSPS2 state types

diff --git a/lightning-liquidity/Cargo.toml b/lightning-liquidity/Cargo.toml
index ff270a7..a29fc36 100644
--- a/lightning-liquidity/Cargo.toml
+++ b/lightning-liquidity/Cargo.toml
@@ -24,6 +24,7 @@ _test_utils = []
 lightning = { version = "0.2.0", path = "../lightning", default-features = false }
 lightning-types = { version = "0.3.0", path = "../lightning-types", default-features = false }
 lightning-invoice = { version = "0.34.0", path = "../lightning-invoice", default-features = false, features = ["serde"] }
+lightning-macros = { version = "0.2", path = "../lightning-macros" }
 
 bitcoin = { version = "0.32.2", default-features = false, features = ["serde"] }
 
diff --git a/lightning-liquidity/src/lsps0/ser.rs b/lightning-liquidity/src/lsps0/ser.rs
index 213e276..70649fe 100644
--- a/lightning-liquidity/src/lsps0/ser.rs
+++ b/lightning-liquidity/src/lsps0/ser.rs
@@ -30,7 +30,7 @@ use crate::prelude::HashMap;
 
 use lightning::ln::msgs::{DecodeError, LightningError};
 use lightning::ln::wire;
-use lightning::util::ser::{LengthLimitedRead, LengthReadable, WithoutLength};
+use lightning::util::ser::{LengthLimitedRead, LengthReadable, Readable, WithoutLength, Writeable};
 
 use bitcoin::secp256k1::PublicKey;
 
@@ -217,6 +217,22 @@ impl wire::Type for RawLSPSMessage {
 #[serde(transparent)]
 pub struct LSPSRequestId(pub String);
 
+impl Writeable for LSPSRequestId {
+	fn write<W: lightning::util::ser::Writer>(
+		&self, writer: &mut W,
+	) -> Result<(), lightning::io::Error> {
+		self.0.write(writer)?;
+		Ok(())
+	}
+}
+
+impl Readable for LSPSRequestId {
+	fn read<R: lightning::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		let s: String = Readable::read(reader)?;
+		Ok(Self(s))
+	}
+}
+
 /// An object representing datetimes as described in bLIP-50 / LSPS0.
 #[derive(Clone, Debug, Copy, PartialEq, Eq, Hash, Deserialize, Serialize)]
 #[serde(transparent)]
@@ -266,6 +282,23 @@ impl Display for LSPSDateTime {
 	}
 }
 
+impl Writeable for LSPSDateTime {
+	fn write<W: lightning::util::ser::Writer>(
+		&self, writer: &mut W,
+	) -> Result<(), lightning::io::Error> {
+		self.to_rfc3339().write(writer)?;
+		Ok(())
+	}
+}
+
+impl Readable for LSPSDateTime {
+	fn read<R: lightning::io::Read>(reader: &mut R) -> Result<Self, DecodeError> {
+		let s: String = Readable::read(reader)?;
+		let val = Self::from_str(&s).map_err(|_| lightning::ln::msgs::DecodeError::InvalidValue)?;
+		Ok(val)
+	}
+}
+
 /// An error returned in response to an JSON-RPC request.
 ///
 /// Please refer to the [JSON-RPC 2.0 specification](https://www.jsonrpc.org/specification#error_object) for
@@ -933,3 +966,19 @@ pub(crate) mod u32_fee_rate {
 		Ok(FeeRate::from_sat_per_kwu(fee_rate_sat_kwu as u64))
 	}
 }
+
+#[cfg(test)]
+mod tests {
+	use super::*;
+
+	use lightning::io::Cursor;
+
+	#[test]
+	fn datetime_serializaton() {
+		let expected_datetime = LSPSDateTime::from_str("2035-05-20T08:30:45Z").unwrap();
+		let mut buf = Vec::new();
+		expected_datetime.write(&mut buf).unwrap();
+		let decoded_datetime: LSPSDateTime = Readable::read(&mut Cursor::new(buf)).unwrap();
+		assert_eq!(expected_datetime, decoded_datetime);
+	}
+}
diff --git a/lightning-liquidity/src/lsps2/msgs.rs b/lightning-liquidity/src/lsps2/msgs.rs
index 699e5a3..21e1af8 100644
--- a/lightning-liquidity/src/lsps2/msgs.rs
+++ b/lightning-liquidity/src/lsps2/msgs.rs
@@ -21,6 +21,7 @@ use bitcoin::secp256k1::PublicKey;
 
 use serde::{Deserialize, Serialize};
 
+use lightning::impl_writeable_tlv_based;
 use lightning::util::scid_utils;
 
 use crate::lsps0::ser::{
@@ -122,6 +123,17 @@ pub struct LSPS2OpeningFeeParams {
 	pub promise: String,
 }
 
+impl_writeable_tlv_based!(LSPS2OpeningFeeParams, {
+	(0, min_fee_msat, required),
+	(2, proportional, required),
+	(4, valid_until, required),
+	(6, min_lifetime, required),
+	(8, max_client_to_self_delay, required),
+	(10, min_payment_size_msat, required),
+	(12, max_payment_size_msat, required),
+	(14, promise, required),
+});
+
 /// A response to a [`LSPS2GetInfoRequest`]
 #[derive(Clone, Debug, PartialEq, Eq, Deserialize, Serialize)]
 pub struct LSPS2GetInfoResponse {
diff --git a/lightning-liquidity/src/lsps2/payment_queue.rs b/lightning-liquidity/src/lsps2/payment_queue.rs
index d6474dc..003939d 100644
--- a/lightning-liquidity/src/lsps2/payment_queue.rs
+++ b/lightning-liquidity/src/lsps2/payment_queue.rs
@@ -9,6 +9,7 @@
 
 use alloc::vec::Vec;
 
+use lightning::impl_writeable_tlv_based;
 use lightning::ln::channelmanager::InterceptId;
 use lightning_types::payment::PaymentHash;
 
@@ -62,12 +63,21 @@ impl PaymentQueue {
 	}
 }
 
+impl_writeable_tlv_based!(PaymentQueue, {
+	(0, payments, optional_vec),
+});
+
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub(crate) struct PaymentQueueEntry {
 	pub(crate) payment_hash: PaymentHash,
 	pub(crate) htlcs: Vec<InterceptedHTLC>,
 }
 
+impl_writeable_tlv_based!(PaymentQueueEntry, {
+	(0, payment_hash, required),
+	(2, htlcs, optional_vec),
+});
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 pub(crate) struct InterceptedHTLC {
 	pub(crate) intercept_id: InterceptId,
@@ -75,6 +85,12 @@ pub(crate) struct InterceptedHTLC {
 	pub(crate) payment_hash: PaymentHash,
 }
 
+impl_writeable_tlv_based!(InterceptedHTLC, {
+	(0, intercept_id, required),
+	(2, expected_outbound_amount_msat, required),
+	(4, payment_hash, required),
+});
+
 #[cfg(test)]
 mod tests {
 	use super::*;
diff --git a/lightning-liquidity/src/lsps2/service.rs b/lightning-liquidity/src/lsps2/service.rs
index 3aeca0e..d61ad70 100644
--- a/lightning-liquidity/src/lsps2/service.rs
+++ b/lightning-liquidity/src/lsps2/service.rs
@@ -38,6 +38,7 @@ use lightning::ln::msgs::{ErrorAction, LightningError};
 use lightning::ln::types::ChannelId;
 use lightning::util::errors::APIError;
 use lightning::util::logger::Level;
+use lightning::{impl_writeable_tlv_based, impl_writeable_tlv_based_enum};
 
 use lightning_types::payment::PaymentHash;
 
@@ -372,6 +373,29 @@ impl OutboundJITChannelState {
 	}
 }
 
+impl_writeable_tlv_based_enum!(OutboundJITChannelState,
+	(0, PendingInitialPayment) => {
+		(0, payment_queue, required),
+	},
+	(2, PendingChannelOpen) => {
+		(0, payment_queue, required),
+		(2, opening_fee_msat, required),
+	},
+	(4, PendingPaymentForward) => {
+		(0, payment_queue, required),
+		(2, opening_fee_msat, required),
+		(4, channel_id, required),
+	},
+	(6, PendingPayment) => {
+		(0, payment_queue, required),
+		(2, opening_fee_msat, required),
+		(4, channel_id, required),
+	},
+	(8, PaymentForwarded) => {
+		(0, channel_id, required),
+	},
+);
+
 struct OutboundJITChannel {
 	state: OutboundJITChannelState,
 	user_channel_id: u128,
@@ -379,6 +403,13 @@ struct OutboundJITChannel {
 	payment_size_msat: Option<u64>,
 }
 
+impl_writeable_tlv_based!(OutboundJITChannel, {
+	(0, state, required),
+	(2, user_channel_id, required),
+	(4, opening_fee_params, required),
+	(6, payment_size_msat, option),
+});
+
 impl OutboundJITChannel {
 	fn new(
 		payment_size_msat: Option<u64>, opening_fee_params: LSPS2OpeningFeeParams,
@@ -492,6 +523,13 @@ impl PeerState {
 	}
 }
 
+impl_writeable_tlv_based!(PeerState, {
+	(0, outbound_channels_by_intercept_scid, required),
+	(2, intercept_scid_by_user_channel_id, required),
+	(4, intercept_scid_by_channel_id, required),
+	(_unused, pending_requests, (static_value, new_hash_map())),
+});
+
 macro_rules! get_or_insert_peer_state_entry {
 	($self: ident, $outer_state_lock: expr, $message_queue_notifier: expr, $counterparty_node_id: expr) => {{
 		// Return an internal error and abort if we hit the maximum allowed number of total peers.